Method and apparatus for converging local area and wide area wireless data networks

ABSTRACT

A converged network accessible by wireless client devices includes a wide area wireless network, a local area wireless network, and a gateway linked to the wide area and local area wireless networks for integrating access to the networks by the wireless client devices

RELATED APPLICATION

This application is a continuation of Ser. No. 10/173,084, filed Jun.17, 2002, which application was based on Ser. No. 60/299,126, filed Jun.18, 2001.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to wireless data networks and,more particularly, to a method and apparatus for converging local areaand wide area wireless data networks.

2. Description of Related Art

Wireless data technologies are used to provide Internet and othernetwork access to mobile client devices such as, e.g., laptops, personaldigital assistants (PDAs), and smartphones. With the growing popularityof the Internet and the increasing mobility demands from end users,there has recently been increased interest and activity in wireless datanetworks. Some wireless data technologies are designed to support widearea coverage, while others are designed for the local area.

In the wide area, cellular operators such as AT&T are presentlydeploying high-speed packet based wireless wide area networks (WANs).Older wide area wireless data technologies have used Cellular DigitalPacket Data (CDPD) and circuit switched data. While these oldertechnologies offer coverage over a large area, they are limited in thebit rates offered (.about. 20 kbps) and accordingly somewhat restrictthe types of applications that could be accessed. With the advent ofhigher-speed technologies such as General Packet Radio Service (GPRS)and Wideband Code Division Multiple Access (WCDMA), cellular operatorsare now building out wireless data networks that will provide moderatelyhigh speed (.about. 100 kbps) access to the Internet. These networks arebased on the so-called 2.5 G wireless data technologies, such as GPRSand 1XRTT. It is expected that these wireless data technologies willprovide convenient access to the Internet over a large coverage area,with each base station in the network typically covering up to severalmiles. Due the relatively higher bit rate, various applications are nowenvisioned that will extend the reach of the Internet to the wirelessworld. Users are expected to access these networks through variousclient devices such as next-generation smart phones as well as PDAs andlaptops with 2.5 G network interface cards.

In the local area, enterprises and universities are now deployingwireless local area networks (LANs) based on the IEEE 802.11b standard.Users with client devices such as laptops and PDAs use an 802.11 networkinterface card that enables them to access the Internet without havingto be attached to a desktop. The current 802.11 technology allows accessat speeds up to 11 Mbps over a range of several hundred feet. Inaddition to replacing traditional Ethernet-based local area networks,these wireless LANs are now also being deployed in novel settings. Ofspecial interest is the increasing deployment of these 802.11 basednetworks in public spaces and hot spots such as, e.g., airports,convention centers, hotels, and even local coffee shops. These hotspotspromise to provide localized wireless access at fast speeds. Thehotspots are typically managed by local wireless Internet serviceproviders (ISPs) such as, e.g., Wayport or by wireless LANinfrastructure integrators such as, e.g., Concourse Communications.

Advantages of WANs include wide coverage and “always on” access. Thesenetworks typically cover large areas of several miles. Due to thepacket-based nature and the large coverage areas of these networks, 2.5G enables data access all the time.

Disadvantages of wide area networks include limited bit rate andexpensive equipment. Compared with the data speeds of several Mbpstypically available in enterprises today as well as the 11 Mbps rateoffered by 802.11b, the data rates achievable with 2.5 G are quitelimited. For example, most 2.5 G networks will offer data rates of onlyup to 144 kbps. Also, the equipment needed to deploy the 2.5 G networksis quite expensive, in line with costs of traditional carrier-scaleswitching systems. A base station, e.g., can typically cost severalhundred thousand dollars.

Advantages of the 802.11 LANs include a high data rate and inexpensiveequipment. Relative to the 2.5 G networks, the wireless 802.11 LANs cansupport peak data rates of up to 11 Mbps in current generationtechnology. Further enhancements to this technology can support up to 54Mbps data rates as well (802.11g and 802.11a). The cost of 802.11equipment is also quite reasonable, and is typically a couple of ordersof magnitude below that of the WAN networks. Also, the 802.11 networksoperate in the unlicensed band. As a result, there are no spectrumacquisition costs associated with wireless LAN deployments.

Disadvantages of 802.11 based networks are limited coverage and no“always on” access. The coverage of each 802.11 base station (calledaccess point) is typically limited to 150-200 ft. Also, since thecoverage areas are limited, it is prohibitively expensive to deploy802.11 based networks over large areas. As a result, it is not practicalto obtain the same benefit of ‘always on’ access for these networks.

BRIEF SUMMARY OF EMBODIMENTS OF THE INVENTION

Some embodiments of the invention are directed to a converged networkaccessible by wireless client devices. The converged network includes awide area wireless network, a local area wireless network, and a gatewaylinked to the wide area and local area wireless networks for integratingaccess to the networks by the wireless client devices.

Some embodiments of the invention are directed to a gateway forconverging access by wireless client devices to a wide area wirelessnetwork and to a local area wireless network. The gateway is linked tothe networks and emulates an interface in the wide area network.

Some embodiments of the invention are directed to a method of operatinga wide area wireless network to provide users of wireless client devicesintegrated access to the wide area wireless network and to a local areawireless network. The method includes detecting the presence of awireless client device in a coverage area of the local area wirelessnetwork, authenticating the user of the wireless client device, andenabling the user to access the local and wide area wireless networkswhen authenticated.

These and other features will become readily apparent from the followingdetailed description wherein embodiments of the invention are shown anddescribed by way of illustration of the best mode of the invention. Aswill be realized, the invention is capable of other and differentembodiments and its several details may be capable of modifications invarious respects, all without departing from the invention. Accordingly,the drawings and description are to be regarded as illustrative innature and not in a restrictive or limiting sense with the scope of theapplication being indicated in the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram illustrating the system architecture for aGPRS network in accordance with the prior art.

FIG. 2 is a schematic diagram illustrating the system architecture for aconverged network using a converged wireless gateway (CWG) for basestation emulation in accordance with some embodiments of the invention.

FIG. 3 is a schematic diagram illustrating deployment of CWGs inaccordance with various alternate embodiments on the invention.

FIG. 4 is a schematic diagram illustrating CWG emulation of a GPRS cellin accordance with some embodiments of the invention.

FIG. 5 is a diagram illustrating a client initialization process inaccordance with some embodiments of the invention.

FIG. 6 is a diagram illustrating a CWG initialization process inaccordance with some embodiments of the invention.

FIG. 7 is a schematic diagram illustrating CWG interfaces in accordancewith some embodiments of the invention.

FIG. 8 is a schematic diagram illustrating a protocol stack for a CWG inaccordance with some embodiments of the invention.

FIG. 9 is a schematic diagram illustrating a per user state machinemaintained by a CWG for each mobile station (MS) in accordance with someembodiments of the invention.

FIG. 10 is a diagram illustrating states maintained by the CWG for usersin accordance with some embodiments of the invention.

FIG. 11 is a schematic diagram illustrating the structure of CWG clientsoftware in accordance with some embodiments of the invention.

FIG. 12 is a diagram illustrating a client authentication process inaccordance with some embodiments of the invention.

FIG. 13 is a schematic diagram illustrating CWG context creation inaccordance with some embodiments of the invention.

FIG. 14 is a schematic diagram illustrating a system architecture for aCWG through SGSN emulation in accordance with some embodiments of theinvention.

FIG. 15 is a schematic diagram illustrating a system design for a CWGwith SGSN emulation in accordance with some embodiments of theinvention.

FIG. 16 is a schematic diagram illustrating system interfaces for anSGSN-based CWG in accordance with some embodiments of the invention.

FIG. 17 is a schematic diagram illustrating a system architecture for aCWG connected through a GGSN in accordance with some embodiments of theinvention.

FIG. 18 is a schematic diagram illustrating a system design for aGGSN-based CWG in accordance with some embodiments of the invention.

FIG. 19 is a schematic diagram illustrating system interfaces for aGGSN-based CWG in accordance with some embodiments of the invention.

FIG. 20 is a diagram illustrating call flow for a GGSN-based CWG inaccordance with some embodiments of the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The present invention is generally directed to a method and apparatusfor integrating wide area and local area wireless networks operated,e.g., by wireless carriers and hotspot operators, respectively. Varioustypes or levels of integration can be provided such as, e.g., AAAintegration, traffic integration, and session integration. Briefly, AAAintegration is the integration of the authentication, authorization, andaccounting functions so that use of both the local and wide areanetworks by a client user is authenticated and billed by one party,e.g., the 2.5 G carrier's network. Traffic integration enables trafficand services from the carrier's network to be available to the 802.11user within the hotspot operator's network. Session integration enablesthe user to have a seamless session as he moves from one network toanother. Integration can be achieved using a client software that runson the 802.11 access device and a server component that is deployedclose to or at the carrier's network and links into the carrier'snetwork.

In accordance with various embodiments, a converged environment isprovided where hotspots and the wide area networks merge with eachother. The following scenario illustrates one example of the use of sucha converged environment: A business user arrives at a hotspot such as,e.g., one at an airport. At the airport, the user gets access tohigh-speed data using a wireless LAN technology. The user then boards arental car shuttle and drives away from the airport and out of the LANcoverage area. Since there is no wireless LAN coverage on the way to therental car pick up location, the user switches to available wide areatechnology, such as 2.5 G, and continues to access the Internet and runapplications without interruption, although at a lower speed. At therental car pickup, 802.11 access is available, and the usertransparently switches to the high-speed network access method. The userthen drives to the hotel, using the wide area 2.5 G network on the way.Finally, there is a 802.11 deployment at the hotel, and the userswitches back to that. Thus, by enabling convergence, the end-user canuse the most appropriate access technology available at a givenlocation. At locations where there is 802.11 access, the user uses thatto get high-speed connectivity. When there is no access, the user stillgets coverage by connecting through the wide area. Further, the userpreferably gets a single bill from a single carrier itemizing the usageat different hot spots. Due to its lower installation cost, 802.11 basedaccess will typically cost much less than the 2.5 G access.

Convergence benefits can also be applied to enterprises, which canprovide access to their services from both local and wide area networks.

As previously mentioned, multiple types or levels of convergence of thewireless LANs and WANs can be achieved. The so-called AAA integration isthe integration of the authentication, authorization, and accountingsystems of the wireless LAN and WAN networks. Currently, wireless ISPsmanage the authentication and billing for wireless LAN usage, whilecellular operators manage billing and authentication for the 2.5 Gusage. It would be advantageous for end users to have only one entityproviding billing and authentication when both networks are used. Thismakes it convenient for the user by not requiring him to get accountswith different wireless ISP's that may be running different hot spots.Further, this integration also delineates customer ownership. A cellularoperator can become the “owner” of the end customer by providing anintegrated billing system. This system can allow the end user to beassociated with a single field in the carrier's billing table.

Through this level of integration, the cellular operators' databaseauthenticates a wireless LAN user, who is also a cellular customer.

Traffic integration between LAN and WAN networks allows traffic andservices from the 2.5 G network to be accessible within the hotspot LANnetwork. Examples of such services can include push-based applicationssuch as paging and messaging that are offered by the cellular operator.While these services can be accessed from the cellular network, theycannot be easily accessed from the LAN. By allowing traffic to flow fromthe carrier's network into the wireless LAN network, these services canbe made accessible to wireless LAN users in the hotspot.

Because of their larger installed base of users, carriers are typicallyable to more affectively broker relationships with various applicationproviders compared to smaller hotspot operators. Accordingly it is oftendifficult for hotspot operators to provide the same rich set ofapplications and services to their users. By integrating traffic flows,the end user can get access to these applications within hotspots aswell.

Session integration is another level or type of integration between theLAN and the WAN. Through this level of integration, seamlessconnectivity can be provided as a user moves from one network to theother. In other words, the user maintains a session, no matter whataccess mechanism he is using. A dual mode terminal that can dynamicallyswitch between the two air interfaces can be used to provide sessionintegration.

Network Architecture for Existing WAN and LAN Systems

Currently, 2.5 G wide area wireless networks co-exist with 802.11 basedlocal area network hotspots, with no interaction between the twonetworks. FIG. 1 illustrates current generation wireless dataarchitecture. The upper part of FIG. 1 illustrates the typical systemarchitecture for a GPRS-based 2.5 G network technology. This generalarchitecture is functionally similar for other wireless WAN technologiessuch as CDMA-based 1XRTT technology. A GPRS-based architecture isdescribed for ease of explanation, but it should be understood thatvarious embodiments of the invention can also be used with the 1XRTTtechnology and other wireless technologies.

The 2.5 G GPRS network 8 architecture is typically managed by a cellularoperator such as, e.g., AT&T Wireless. This network can support voice aswell as data transactions. Mobile stations (MS) 10, which are alsodescribed herein as wireless client devices (such as, e.g., laptops,cell phones or PDAs with a GPRS NIC), connect to a base station (BS) 12.Multiple base stations 12 connect into a base station controller (BSC)14. Voice traffic is sent from the BSC 14 to the Mobile Switching Center(MSC) 16. A Packet Control Unit (PCU) installed at the BSC 14 separatesout data traffic coming from the MS 10. The data traffic is managed bythe cellular operator's wireless data network. More, specifically, thedata traffic goes to a SGSN (Serving GPRS Service Node) 18. A carrier'snetwork typically has multiple SGSNs. The SGSNs authenticate mobileusers by querying an HLR 20 (Home Location Register) database. The SGSN18 is also responsible for managing traffic, and it routes data trafficover the carrier's GPRS network to a Gateway GPRS Service Node (GGSN)22. The GGSN 22 is a border router which routes traffic to and from theGPRS network into the public Internet. As a user moves across cells, theuser becomes associated with different SGSNs. The SGSNs are responsiblefor managing the mobility of the user. FIG. 1 shows specific interfacesbetween different elements of the WAN network 8. These interfaces aredefined by the GPRS standard published by the ETSI and the 3GPP.

The lower portion of FIG. 1 shows the network architecture for localwireless LANs 24 deployed, e.g., in hot spot locations. As mentionedearlier, hotspots can be deployed at various locations such as, e.g., atairports, convention centers, and in the local coffee shops. Hotspotscan be classified into two general categories: mini hotspots and megahotspots. A mini hotspot is a relatively small deployment such as, e.g.,in a coffee shop. A mini hot spot deployment typically comprises asingle wireless LAN 802.11 based access point (AP) 26 and providesconnectivity into the Internet typically over a DSL, T1, or a leasedline. A mega hotspot is a deployment that supports a set of accesspoints and covers a moderate sized area such as, e.g., a conventioncenter. Such a deployment typically has multiple APs connected throughEthernet switches and a router to the public Internet typically over aT1 or a leased line.

The hotspots are typically managed and operated by wireless ISP's (WISP)or wireless system integrators. Users with laptops or PDA's with 802.11based network interface cards (NIC's) can use the 802.11 based wirelessnetwork to access the Internet.

Users are typically authenticated by the hotspot operator's AAA systemthat typically uses RADIUS (RFC 2865, 2866).

LAN/WAN Integration Using a CWG

Currently, WANs 8 operated by cellular carriers and LANS 24 operated bywireless ISPs are separate, i.e., not integrated. Each operator managesits own network and has its own customers. Various embodiments of thepresent invention are directed to converging the wide area and localarea wireless networks through an appliance called the ConvergedWireless Gateway (CWG).

Briefly, the CWG enables integration at various levels including (1)authentication of the wireless LAN user against his profile in the GPRSnetwork; (2) enabling GPRS services and traffic to flow through thewireless LAN hotspot; and (3) managing seamless sessions between GPRSand wireless LAN.

FIG. 2 generally illustrates the system architecture for integratingLANs 50 with WANs 52 in accordance with some embodiments of theinvention. In these embodiments, convergence is achieved using a CWG 54and a CWG client 56. The CWG 54 is a gateway between the wireless LAN 50and the GPRS network 52. The CWG 54 can be deployed in multiple ways byemulating different interfaces within the GPRS network 52 as illustratedin FIG. 3.

A CWG 54′ can be deployed, e.g., by emulating a basestation/packetcontrol unit (BS/PCU) and connecting to the SGSN 18 within the GPRSnetwork. Through this design, the CWG 54′ can make a wireless LAN hotspot look like a GPRS cell to the SGSN. To accomplish this, the CWGemulates several functions within the mobile station, the BS, and thePCU. By masquerading as a GPRS cell, this design enables the wirelessLAN cell to leverage several key features and functionalities within theGPRS network. In particular, it can leverage the authentication andmobility management capabilities of the SGSN.

Alternatively, a CWG 54″ can be deployed by emulating a SGSN and byconnecting to the GGSN 22 and other SGSNs 18 in the GPRS network. Fromthe GPRS network perspective, the CWG 54″ looks like a SGSN, while fromthe LAN side, the CWG looks like a LAN interface. In this approach, theCWG emulates the SGSN and can leverage the mobility managementinfrastructure of the GPRS network.

As a further alternative, a CWG 54′″ can be deployed as a GGSNinterface. In this approach, the CWG connects to the GGSN 22 from theexternal side, as against the GPRS network side. In this case, the CWGis a gateway that connects to the GGSN and leverages authenticationinfrastructure within the GPRS network.

A CWG client 56 is installed on the MS 10. The client software caninclude information downloaded by the operator when the user firstsubscribes to hotspot access. The client is responsible for conveyingidentification information as well as for assisting in traffic andmobility management. Note that the client software is generally neededto provide session and traffic integration and is optional if only AAAintegration is desired. If present, however, the client softwarecommunicates with the CWG to authenticate the user with the GPRSnetwork.

The following is a more detailed description of the CWG deployment usingBS emulation. (Description of CWG deployment using SGSN emulation andGGSN emulation in accordance with alternate embodiments will be providedfurther below). The CWG connects the hotspot to the SGSN in the GPRSnetwork. When connecting to the SGSN, the CWG can emulate the standardinterface used by native GPRS base stations connecting into the SGSN.Specifically, the CWG can connect to the SGSN over a frame relayconnection, as specified by the GPRS standard. This link can be definedto be the Gb interface as per the GPRS specifications (3GPP TS23.060).

Each CWG can have a frame relay connection to interface with the SGSN.There are several possible locations where the CWG can be deployedincluding, e.g., the following: (1) at the hotspot, connected to an edgerouter; (2) at an ISP POP or data center; (3) hosted anywhere on theInternet; and (4) within the carrier's premises or in proximity to theSGSN.

While any of these deployments can be used, locations (3) and (4) arepreferred. This design choice simplifies the deployment of the CWG sinceit is not necessary to provision additional T1 or E1 connections fromeach hotspot area. Also, this architecture permits users from differentcarriers to access a given hotspot without requiring each carrier toprovision a CWG interface at each hotspot.

FIG. 4 describes this system design in greater detail. In a typical GPRSnetwork, multiple GPRS cells 60 typically are grouped into a routingarea 62. One or more routing areas are controlled by a SGSN 18. SGSNscommunicate with the HLR 20 to get authentication information.

The CWG 54′ can be connected between an 802.11 cell and the SGSN 18. Ina preferred embodiment, the CWG is located within or close to thecarrier premises. A Frame Relay link is provisioned between the CWG andthe SGSN. The hotspot users connect to the CWG over the public Internetor via a dedicated connection. The CWG makes the 802.11 cell appear tothe SGSN as any other GPRS cell.

Typically, a few hotspots will be associated with a CWG. Thisassociation can be based on geographic proximity. This CWG in turn isconnected to the most proximate SGSN. A CWG connects to only one SGSN.More than one CWG may be connected to a particular SGSN.

A more detailed description is provided below of the operation of a CWGbased system.

1. To use the converged networks, the end user typically signs up withhis wireless operator (e.g., AT&T wireless) to start using 802.11hotspots. This can be done, e.g., through a web interface.

2. The operator downloads a relatively simple client software on theuser's 802.11 device. The client software is used for managing thesessions between the LAN and the WAN. The client may optionally includethe user's identification within the GPRS network. The user'sidentification can be encrypted and stored in non-volatile memory on the802.11 device. In some embodiments, the client is not used if, e.g.,only AAA integration is desired.

3. The CWG client detects the presence of a CWG when it comes within an802.11 hotspot affiliated with the converged network. Specifically, theCWG gateway can periodically broadcast beacons advertising its presence.If the CWG client detects a CWG broadcast message, it requestsauthentication with the CWG.

4. The 802.11 hotspot can be configured to let the authenticationmessages from the CWG client go out of the network. (Currently, the802.11 hotspot will authenticate its users before letting any traffic goout of the hotspot.)

5. The CWG, in turn, requests authentication with the GPRS network onbehalf of the 802.11 user, by presenting itself as a GPRS client to theSGSN.

6. The CWG goes through the authentication process with the GPRS networkthrough the SGSN. The SGSN authenticates the user. The CWG then conveysthe authentication to the CWG client and enables the user to access theGPRS network as if it were a GPRS user. Once authenticated, the CWG alsoenables traffic to be routed from the 802.11 network over the GPRSnetwork.

7. When the user sends traffic, certain services and applications areallowed to go through the carrier's network. These services areidentified within the client software. Other traffic is routed over thepublic Internet directly.

The key functionality of the CWG can therefore be summarized as follows:(1) logical emulation of a GPRS mobile station; and (2) physicalemulation of a GPRS Base Station and Packet Control Unit.

The CWG architecture has several advantages. First, it provides easyaccess to the HLR. By emulating the MS to the SGSN, the CWG can accessauthentication information within the HLR by leveraging the SGSN. Itdoes not have to replicate any of these functions or tap into thedatabase itself. Second, the CWG architecture facilitates mobilitymanagement. By leveraging the SGSN infrastructure, it is possible toachieve seamless mobility. As the end user moves from a GPRS cell to aCWG-controlled 802.11 cell, the SGSN manages the mobility as if the userwere moving between GPRS cells. Third, the CWG can be easily deployed.The architecture of locating CWG close to carrier's network makes itpossible to share the CWG among multiple hotspots, and does not requirespecial provisioning within each deployment. Fourth, the CWG providesmulti-carrier support. Since a CWG is not required at each hotspot,users from multiple carriers can access a hotspot location. The clientdirects the traffic to the appropriate CWG in the correspondingcarrier's network.

The three primary parties involved in the converged operation are theend-user, the hotspot operator, and the carrier. To enable convergednetwork access, each will generally to make some changes to theirrespective system. For example, as will be described below, the end-userruns a CWG client, which can be downloaded when the user signs up forthe CWG service. Also, the hotspot operator may need changes to allowroaming users to pass through its network. Specifically, users who donot belong to the hotspot ISP should be able to get authenticated withthe carrier and their traffic should subsequently be passed through.Also, the wireless carrier will deploy the CWG to enable theconvergence. The CWG is set up initially to connect to the appropriatenetwork elements. It should also be configured to broadcast itself tothe hotspots.

As mentioned previously, the 802.11 user can sign up with the wirelessWAN operator to get access to hotspot locations. An example procedurefor this user initialization is described in FIG. 5. The user can firstcontact the WAN cellular operator (e.g., the cellular operator's website 66) to register for hot spot access. The carrier requests userinformation such as, e.g., his mobile phone number, the type of devicehe will use to access the network from, etc. On receiving the response,the carrier downloads the appropriate client software 56 on the user'sdevice 10. The client can support various user devices 10 such as PDAsand laptops. The carrier also receives the user's information in the 2.5G network from the HLR 20. This information is then encrypted and storedonto the user's device 10. A “soft authentication” approach ispreferably used. Alternatively, the user can be authenticated throughother mechanisms such as login/password or a hardware SIM. The carrieralso sets up default CWG locations within the client software. (Tosubsequently modify the client software, the CWG 54′ can triggerautomatic updates and downloads depending on the version of the clientsoftware.) Once this initial setup is done, the client is ready toaccess the GPRS network.

Currently, most hotspot operators control access to the hotspot. A useris expected to sign up for hotspot usage with a wireless ISP. When theuser comes to the hotspot and starts transmitting data, the hotspotintercepts the traffic. It queries the user for a login/password beforeletting traffic pass through. Once the user is authenticated, thehotspot allows that user to access the network.

The hotspot can be programmed to allow the CWG authentication messagesto go through to the public network (to the CWG). Once the user isauthenticated, it can allow the traffic from the user to flow through.Also, the hotspot device can be configured to broadcast the CWG beaconmessages. These features can be supported relatively easily withinexisting authentication mechanisms supported by the hotspot. Mosthotspot operators today deploy the hotspot with a NAS (Network accessserver) that blocks user traffic before authentication. The CWG can bedesigned to interface with the NAS.

The CWG client sends identification information to the CWG. It can alsoassist in other mobility and billing functions as described below.

The client is designed to start its operation when it detects a CWG.This ensures that the CWG functions are active only in designatedconvergent areas (and not in every place that might have a 802.11deployment such as a home). As a result, the CWG needs to announce itspresence to CWG clients. This can be accomplished using beacons, whichthe CWG can periodically send out. A beacon is typically a short IPpacket that gives its location. The default beacon interval is 100 msbut it can be changed as desired.

The CWG client listens to these beacons to recognize whether it is in ahotspot that is covered by the CWG and starts activating itself with theGPRS network through the CWG. Since the CWG is typically not locatedwithin the hotspot, it is important for the CWG's beacons to reach thehotspot. To accomplish this, the CWG can be programmed with locations ofall hotspots that are enabled to access the GPRS network. As morehotspots sign up for CWG access, these locations are programmed withinthe CWG.

As shown in FIG. 6, the CWG broadcasts its presence beacons periodicallyto all enabled hotspot locations. These locations, in turn, broadcastthe beacons to respective internal networks.

Hotspot locations within a region can be associated with a particularCWG. This association can be determined based on geographic proximity.This CWG sends its broadcasts to those locations. Thus, clients in thatregion get associated with that CWG. This CWG, in turn, is connectedpreferably to the most proximate SGSN. A CWG connects to one SGSN. Morethan one CWG may be connected to a particular SGSN.

FIG. 7 illustrates the physical and the protocol interfaces for the CWG54′. The CWG client 56 sends IP packets to the CWG 54′ over the publicInternet. The AP 26 within the hotspot is allowed to forwardauthentication requests as well as traffic for CWG clients 56. The CWG54′ receives TCP/IP packets over the Internet from the hotspot. The CWG54′ converts these packets to the GPRS format, in the IP and SNDCP (asdefined by 3GPP TS 23.060) stack, and sends the converted packets to theSGSN 18. The SGSN 18 expects input from the GPRS BSS/PCU over a FrameRelay link. In order to emulate the BSS/PCU, the CWG 54′ sends outputpackets over Frame Relay to the SGSN 18. Specifically, the CWG outputinterface resembles the Gb interface as specified in the GPRS standard.

As previously mentioned, the CWG can also allow traffic integration.Specifically, for services hosted by the carrier, traffic is allowed toand from the hotspot user to go through the carrier's network. In thiscase, the CWG client sends traffic to the CWG. This can be accomplished,e.g., either by tunneling the packets or by changing the header to sendto the CWG. The CWG can then reroute the packets appropriately.

The 802.11 user can be identified within the GPRS network through hisIMSI (a 15 bit unique non-dialable number that identifies the subscriberand subscription within the GSM network) identifier, while theparticular session in the hot spot is associated with an IP address. TheCWG can maintain this mapping between the two networks.

FIG. 8 shows the protocol stack within the CWG 54′. Specifically, theCWG 54′ emulates a combination of the protocol stacks on the mobilestation and the Base Station PCU. The stack for the transmission and thesignaling plane is shown in FIG. 8. The CWG 54′ gets incoming IP packetsfrom the MS 10 and adds SNDCP headers as well as BSSGP (as defined in3GPP TS 23.060) headers. The receiving SGSN 18 processes these packetsas though they came from a GPRS MS over the GPRS BSS link. On thesignaling side, the CWG 54′ maintains the GPRS Mobility Management andSession Management states for each user that it emulates.

The CWG maintains a set of states and data structures for each user whoconnects through it. For each user, the permanent IMSI identifiermaintained by the GPRS network is used for authentication and billing.For each session, the 802.11 user might have a different IP addresswithin the hot spot. Each session is identified on the hot spot side byan IP address. The CWG maintains a mapping of the IP address with theIMSI ID on the GPRS side.

Each MS 10 can be in one of three GPRS states: idle, ready, and standby.An MS moves from idle state to ready state after it attaches itself withthe GPRS network. It moves from the ready state to the standby stateafter extended period of inactivity. It moves from standby state toready state when it is ready to send/receive data. In a typical GPRSnetwork, the MS maintains these states. In the converged network, theCWG 54′ maintains these states for each hotspot user it supports. FIG. 9shows a state machine that the CWG 54′ maintains for each MS 10.

FIG. 10 shows the state maintained for each user within the CWG 54′. TheIMSI number from the GPRS network uniquely identifies each user. Thesession is identified by the IP address from the hotspot. The shaded box68 shows the state specific to the CWG, including the IP address, 802.11security information, as well as specific charging information that maybe collected. The CWG 54′ also maintains the Mobility context 70 as wellas the PDP context 72 for each user, which would otherwise have beenmaintained by the GPRS MS.

The architecture of the client software on the MS is now described. Asmentioned earlier, when a user subscribes to a hotspot service from thewireless carrier, the operator downloads a thin client and some softwareon the user terminal. The operator also stores identificationinformation on the client. (If the client has a SIM Card functionality,this information could be read from the SIM card as well).

FIG. 11 shows the general structure of the client software 74. Thisarchitecture does not require a GPRS stack to be present on the client.

The functions of the application layer 76 software can include thefollowing: (1) detect 802.11 network interface activity to determine ifit is in the 802.11 vicinity; (2) scan for CWG beacons and request forlogin with the CWG; (3) send identification information to the CWG; (4)tunnel and de-tunnel packets to the CWG for applications that need to gothrough the GPRS network; and (5) billing and monitoring capability forusage tracking.

The client can be responsible for determining which packets are tunneledto the CWG. Authentication information is sent to the CWG. In case ofapplication traffic, the CWG client either sends the traffic directly tothe hotspot, or tunnels it to the CWG. In the first case, the hotspotallows the traffic to go through as if it were normal 802.11 traffic. Inthe second case, the CWG client tunnels the traffic to the CWG,emulating a point-to-point link. The CWG then detunnels the data,converts it to GPRS format, and sends it to the SGSN. For incomingtraffic, the CWG receives data from the GPRS network, tunnels it to theCWG client over the public Internet, and the client detunnels thepackets. Tunneling can be accomplished either by a IP in IP tunnel, orby changing header information.

To determine which services need tunneling and which do not, the clientis programmed with applications that are directed to the GPRS network.As new applications are added, the client can be updated as needed. Thiscan be accomplished through the CWG checking the version of the clientand automatically upgrading it, if necessary.

In order to enable seamless sessions, the client should support multipleaccess technologies. For instance, a client can have a dual mode NIC,with GPRS and 802.11 support. One example of such a dual mode card isthe so-called “D211” card available from Nokia. If the user starts asession in the GPRS network, but moves to a hotspot region, the terminalsenses the presence of a 802.11 interface. In this case, it is preferredthat the user switch over the 802.11 network. This preferably happenstransparent to the user. While this happens, the client's session shouldalso remain active. Dual mode NICs should have driver support toseamlessly transfer the application traffic to the appropriate driver.(Specifically, the selection of the appropriate air interface can bedone by either signal strength or by pre-defined preferences.)

If the user has two network interface cards, additional softwarefunctionality can be supported on the NIC so as to determine the networkinterface to forward the traffic to. For example, a network layer shimmodule that will send traffic to the appropriate NIC can accomplishthis.

The sequence of operation is shown in the call flows of FIG. 12 and FIG.13. To get authenticated, the 802.11 terminal 10 needs to first ‘attach’itself to the GPRS network. This process includes authentication withthe HLR 20. FIG. 12 shows the different steps in the process. The MS 10requests login into the GPRS network. The CWG 54′ queries the MS for itsGPRS-specific information. This information can be stored into the MS atthe time the user subscribed for the carrier's hotspot service. Theclient 56 on the MS 10 provides this information to the CWG 54′,preferably transparent to the enduser. The CWG 54′ in turn makes anattach request to the SGSN 18 on behalf of the user. The SGSN 18processes this as a native GPRS attach process. Once the GPRS user hasbeen attached, the user is authenticated into the network. Once the useris authenticated, the MS is in the ‘ready’ state.

Once a MS is attached, a Packet Data Protocol (PDP), e.g., IP, contextis created for each data session. The CWG creates the PDP context asshown in FIG. 13. In case of pull applications, the MS 10 requests a PDPsession to be created. This is shown in step 2 in FIG. 13. For pushapplications, when data is received for a user at the GGSN 22, the GGSNqueries the HLR 20 for the SGSN 18 controlling the user and sends arequest through the SGSN 18 to the CWG 54′ to create a PDP context forthe session. The CWG 54′ in turn creates a session and then traffic canbe communicated to the MS 10 through the CWG 54′.

The attach step is sufficient to authenticate the 802.11 hotspot userinto the GPRS network if only AAA integration is desired. For trafficintegration, a PDP context is to be created.

The CWG architecture has an inherent ability to support seamlesssessions and session mobility. As previously mentioned, the CWG enablesthe 802.11 hotspot to appear to the SGSN as a GPRS cell. As a result,the GPRS network sees an attached end user even when he is in a 802.11network. Consequently, as the user moves from one cell to another, theSGSN manages mobility of the user as if it were a GPRS user.

To understand further how session integration works, consider the casewhere the end user started a session within the GPRS network. Alsoassume that the user has a dual mode terminal that is capable ofaccessing both air interfaces. The terminal can be designed to switchfrom the WAN (GPRS) interface to the 802.11 interface. This switch maybe parameterized based on signal strength, giving priority to the 802.11interface when present. When the MS detects a 802.11 network, the clienton the MS sends a request to the CWG to attach itself to the GPRSnetwork. When the CWG sends the attach information, the SGSN sees thatthe client was already attached from a previous base station.Consequently, it manages the mobility process as it would for a typicalGPRS user moving from one BS to another. If the previous BS wascontrolled by the same SGSN, routing information does not need to beconveyed anywhere else. If the previous BS was attached to a differentSGSN, the SGSN contacts the old SGSN, gets the information, andcontinues operation. When the user then moves back onto the WAN network,the new BS sends information to the SGSN and the same process repeats.Thus, session mobility is automatically supported by the inherent designof the CWG architecture.

One component of the AAA integration functionality is integratingbilling information. Carriers can support an ‘all you can eat’ type ofbilling model for hotspot usage, where the user is charged a flat feeand can access any amount of data. In this case, there is no specialneed to measure actual data usage. However, if the carrier is interestedin determining the actual amount of data used, the type of service used,or duration, the CWG client can be enhanced to collect some of thebilling information. Since the data may not all flow from the CWG, theclient can measure this information. This information can be obtained byreading the packets transferred at the network interface. The trafficthat flows through the actual carrier's network can be metered by theSGSN as normal GPRS traffic.

The network architecture for the CWG to operate with the GPRS network isnow described. As previously mentioned, the CWG concept can be extendedto support several interfaces. For instance, the CWG can allowintegration between 802.11 and CDPD or other circuit switched data.Similarly, the CWG can be designed to support other 2.5 G technologies,such as 1XRTT. Other wireless data technologies, such as Metricom orprivate wireless networks can also be extended to connect to thecarrier's core data network through the CWG.

Other possible features included within the CWG are now described. Inaddition to the AAA, traffic, and session integration functions, the CWGcan be expanded to support several other features. First, a cache can beincluded within the CWG. This can provide fast access to frequentlyaccessed information from the hotspot. In addition, this can lead to asaving of backhaul bandwidth from the hotspot. Second, since the billingsystem for the hotspots could be different from the billing policiesdeployed in the GPRS network, the CWG can collect billing informationfor the 802.11 sessions, such as application type, volume of data, QoS,session duration etc. This information can be stored in IPDR (IP datarecords as specified by ipdr.org consortium) format and can be providedto the carrier's billing system. Third, the CWG can also manage mobilitywithin the LAN, as clients move from one AP to another. Fourth, sincethe devices used in the hot spot could have a form factor different fromthe form factor that the applications are designed for, a transcodingfunctionality could also be included within the CWG.

CWG Deployment Using SGSN Emulation

CWG deployment using SGSN emulation is now described. This alternativeapproach lets the CWG function as an SGSN. One advantage of thisapproach is that it avoids the need to process the Gb interface and theframe relay connection. This is of advantage because of the reducedcomplexity as well as the reduced overhead of additional protocollayers. Also, this design leverages a lot of the core SGSNfunctionality, which is well-defined.

FIG. 14 illustrates the system architecture for the CWG 54″ through SGSNemulation. The CWG 54″ emulates an SGSN 18 on the GPRS network side andan IP interface on the wireless LAN side. The CWG 54″ implements a Gninterface to communicate with other SGSNs 18 and GGSN 22 over the GTPprotocol. It also interfaces with the HLR 20 over the Gr interface toget authentication information.

On the LAN side, traffic from the hotspot is directed through the CWGfollowing a network aggregator. The network aggregator can have adedicated link that connects to the CWG.

FIG. 15 illustrates the operation principle of the CWG 54″. The CWGconnects to 802.11 hotspots and appears to be a SGSN from the GPRSnetwork point of view. As a user moves from the WAN to the LAN, heattaches to the hotspot. This routes traffic to the CWG 54″. The CWGauthenticates the user as if it were authenticating a GPRS user by doinga GPRS attach. It receives authentication information from the terminalsimilar to the case described in the BS emulation approach. The CWGworks with the SGSN 18 to manage a handoff, since to the other SGSN itappears that the user is just moving to a different SGSN.

As shown in FIG. 16, the CWG 54″ interfaces with the SGSN 18 over a Gnlink. It also connects to the GGSN 22, HLR 20 and other components inthe GPRS network as a SGSN. On the hotspot side, it receives hotspotdata over a dedicated link coming from the hotspot.

CWG Deployment Through a GGSN Interface

FIG. 17 shows an alternate system architecture for the CWG where the CWGconnects to the GPRS network through the public Internet. Thisarchitecture allows the carrier and the hotspot operator to integratethe LAN and WAN networks without having to deploy additional connectionsfrom the CWG to the SGSN. Accordingly, one advantage of thisarchitecture is its ease of deployment.

This architecture comprises three components: the CWG, software modulesassociated with traffic aggregators in the hotspot, and client softwareon the MS.

The CWG 54′″ is attached to the public Internet side of the GGSN 22. TheCWG can be attached to the GGSN, along with other servers that ittypically hosts. The CWG 54′″ is responsible for communication with theclients in the hot spot locations. It receives authentication requestsfrom the MS 10, authenticates the user with the GPRS network 52, andthen allows traffic to be pushed to the MS 10 in the hotspot 50.

Software modules associated with traffic aggregators 80 in the hotspotare responsible for gating access to the network before the 802.11 useris authenticated. The traffic from multiple mini hotspots is typicallyaggregated somewhere in the wireless hot spot operators' network beforebeing sent out on the public Internet. Similarly, in the mega hotspot,concentration devices 82 (e.g., Cisco's Broadband service manager BBSM)collect all the traffic from the mega hotspot before routing it to thepublic Internet. In both these cases, there is need to firstauthenticate the user with the WAN before the traffic can go through.The GGSN-based CWG design addresses this through a small software modulethat is added to the existing hotspot aggregation software. Thissoftware could be either integrated into the existing hotspotaggregation software or provided through a separate device. In FIG. 17,this is shown as the shaded part in the mega hotspot and the small boxfor the mini hot spot aggregation point.

Client software on the mobile station includes the informationdownloaded by the operator as in the case of the CWG deploymentpreviously described. This software communicates with the CWG toauthenticate the user with the GPRS network.

The system operation logic is described in FIG. 18. Traffic from the802.11 cell is routed over the public Internet to the CWG 54′″, which isconnected to the GGSN 22. The CWG 54′″ uses the GGSN 22 to getauthentication information from the HLR 20 and passes that back to theMS 10 in the hotspot.

In this architecture, the CWG logically emulates the MS and parts of theSGSN functionality.

The interfaces for the GGSN-based CWG 54′″ deployment solution are shownin FIG. 19. For the mini hotspot, the software module is added to theaggregator. This communicates over TCP/IP over the public Internet tothe CWG 54′″. The CWG communicates to the HLR 20 through the GGSN 22.The CWG functionality is to emulate parts of the MS and the SGSNfunctions. For the mega hotspot, the software module is added to theaggregation software and communicates with the CWG as before.

The call flow for the authentication process is shown in FIG. 20.Traffic from the user MS 10 goes to the aggregator software 80. Thisblocks traffic until the user is authenticated. The client softwareaccesses the CWG 54′″, which communicates with the GGSN 22 and HLR 20 toauthenticate the user. Once the user is authenticated, data transfer isenabled. PDP context activation takes place in generally the same way.

Having described preferred embodiments of the present invention, itshould be apparent that modifications can be made without departing fromthe spirit and scope of the invention.

1. An apparatus for use in a wide area wireless network operated by aservice provider and comprising at least one node of a first type thatroutes traffic to and from the wide area wireless network into thepublic Internet, and one or more nodes of a second type each of whichmanage mobility of a wireless client device in the wide area wirelessnetwork, and wherein a given node of the second type authenticates awireless client device by accessing a database associated with the widearea network, wherein the apparatus comprises: a gateway to which anaccess device of a wireless local area network is connectable, thegateway being associated with the wide area wireless network and beingeither (a) connectable to a node of the first type to enable thewireless local area network access device to appear to the node of thefirst type as a node of the second type, or (b) connectable to a node ofthe second type to enable the wireless local area network access deviceto appear to the node of the second type as a base station/packetcontrol unit of the wide area wireless network; and a client softwareprogram having computer executable instructions in a given wirelessclient device to enable the given wireless client device, whileoperating within the wireless local area network, to use the gateway toaccess the database and thereby provide seamless session integration asthe given wireless client device moves between respective coverage areasof the wide area wireless network and the wireless local area network,wherein the gateway provides the seamless session integration, by (a)emulating the node of the second type when the gateway is connected tothe node of the first type, or (b) emulating the base station/packetcontrol unit when the gateway is connected to the node of the secondtype; wherein the gateway generates billing data identifying a chargefor use, by the given wireless client device, of the wide area wirelessnetwork.
 2. The apparatus as described in claim 1 wherein the gateway isan IP-accessible device, the node of the first type is a Gateway GPRSService Node (GGSN) and the node of the second type is a Serving GPRSService Node (SGSN).
 3. The apparatus as described in claim 1 wherein,following an authentication by the gateway, a user of the given wirelessclient device obtains access to a service available in the wide areawireless network.
 4. The apparatus as described in claim 1 wherein thewide area wireless network is a GPRS or lx Radio Transmission Technology(1XRTT) network.
 5. The apparatus as described in claim 1 wherein thedatabase is a Home Location Register (HLR).
 6. The apparatus asdescribed in claim 1 wherein the gateway is deployed at an ISP Point ofPresence (POP) or data center.
 7. The apparatus as described in claim 1wherein the gateway is hosted on the public Internet.
 8. The apparatusas described in claim 1 wherein the wireless local area network is an802.11 network.